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Articles » Magnetic Resonance Imaging » MRI, Placenta

2006-03-02-10 Molar pregnancy © Werner

Molar pregnancy 

Heron Werner, MD, Pedro Daltro, MD

Clínica de Diagnóstico por Imagem (CDPI) & Instituto Fernandes Figueira (IFF) – FIOCRUZ
Rio de Janeiro – Brazil

Hydatidiform mole is divided in complete (absence of embryonic or fetal tissues) and incomplete form (presence of embryonic or fetal tissues). Moles are result from an abnormal fertilization of an empty ovum by a single sperm with a duplicated haploid genome (46, XX karyotype) or, less commonly, dispermy (46, XX).

The complete hydatiform mole represents an enlarged uterus filled with solid material containing vesicles of varying sizes and the absence of the fetus. It contains only paternal chromosomes and constitutes 80% of cases of gestational trophoblastic neoplasia. The partial hydatiform mole is represented by an enlarged placenta containing multiple diffuse lesions. Most of them are triploid (69 XXX, 69 XXY, 69XYY).

On T2-weighted images, a complete mole appears as a heterogeneous mass of high signal intensity that distends the endometrial cavity. Partial molar pregnancy refers to the combination of a fetus with localized placental molar degeneration. Coexistent true trophoblastic disease and a living fetus are rare.

We present magnetic resonance images of a case of partial hydatiform mole in the 16th week. The pregnancy was interrupted.


Sagittal T2 of the uterus shows heterogeneous mass with high signal intensity that distends the endometrial cavity (arrow). Note the fetal legs (blue arrow)

Sagittal T2 (left image) and coronal T2 (right image) of the uterus showing the placental molar degeneration (red arrow) and the fetus (blue arrow)

Axial T2 showing the placental molar degeneration (red arrow). Note the fetal head (blue arrow)

Axial T1 and coronal T2 showing the placental molar degeneration  (arrow).

Coronal T2 showing the enlarged placenta with molar degeneration (red arrow). Note the fetal body (blue arrow)



• Jorge de Rezende. : Obstetrícia. 10a Edição, Guanabara Koogan, 2005.
• Levine D.: Atlas of Fetal MRI. Taylor & Francis 2005.

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